The four-piece, said to be worth around £25 million each after topping the charts worldwide since emerging in the 2010 series of X Factor, have asked fans to share pictures and videos online describing the kind of world they want to live in as part of the action/2015 campaign.

They said: "Time and again our fans have shown how creative and powerful they can be when they unite and that's why we want to all join together to speak out and hopefully make a real and lasting change to the world around us.

"Young people really do have the power to help end poverty, tackle inequality and to stop dangerous climate change.

One Direction ask fans to help them change the world

"Now is the time for us to unite, take action and raise our voices to show that we care about the future of our planet."

The fans contributions will be made into a film to be shown at two UN summits later this year to put pressure on world leaders to hear young people's voices.

Brendan Cox, director of policy and advocacy at Save the Children which is part of action/2015, said: "One Direction is the biggest band in the world and by mobilising the millions of young people in their fanbase they'll shine a light onto the most important issues of our time.

"UN processes are normally worthy but dull. We hope One Direction's work will make this year's key summits not only worthy but a matter of public excitement. Only with that public engagement will whatever is agreed actually get put into practice."